Right along the border that separates Mexico from Southwestern Arizona, is a land of fire, ash and lava.

It's called the Sierra Pinacate.

For some people, it is a land of brutal heat and pitiless isolation.

This is vast.

For me, and many others, it's a wild land of unparalleled beauty inviting exploration.

Funding for In the Americas with David Yetman was provided by Agnese Haury ♪ Funding for In the Americas with David Yetman was also provided by the Guilford Fund.

♪ ♪ In the Americas with David Yetman theme In the middle of the 19th century, the United States purchased from Mexico a large tract of land, called the Gadsden purchase.

Because the line was changed during the purchase, not included in it, was the largest volcanic field in any desert in North America, the Sierra Pinacate.

It's now in Mexico, parts of extending even into Arizona.

Not only is it a land of former fire and smoke and explosions, but it has a significant human history as well.

There's nowhere else on earth quite like it.

The Pinacate volcanic range is so vast, that it is easily visible from outer space, as a dark spot in a desert of sand dunes.

The black color, is mostly lava, it has poured out of fisher█s holes and cones from much of the last 40, 000 years.

The pockmarks are a mixture of cinder cones, well over 400 of them, and craters.

Holes produced by cataclysmic explosions, which number at least eight and are the most dramatic features of the range, in fact, of any range in the Americas.

The darkness of the lava contrasts, most agreeably, with the light brown of the sand.

The largest area of dune fields in the Americas.

The Sierra Pinacate is not easy to reach.

The few roads are rough and are controlled by Mexican national park service.

The east side where visitors must register, has the better roadways, dirt tracks that are graded every once in awhile.

It's best to visit this rugged dry range with friends, a small group of us will camp in an unimproved campground in a most unusual location.

The middle of a cinder cone.

Included are my Mexican colleague and friend, ecologist Alberto Búrquez and my brother, geologist Dick Yetman.

Alberto has a special affinity for the Sierra Pinacate, he was assigned to, selected by the Mexican government in the early 1990s, to demonstrate the significance of Pinacates to the Mexican nation.

We're here thirty miles from the nearest reliable source of water hot!

If we want to go to the top of that hill, we█re nuts.

But three-hundred years ago, some intrepid souls did it.

Well yes.

Father Kino was a Jesuit, decided to go on top of that hill and look towards the sea to be sure that Baja California was a peninsula.

Well for sure you can see the sea, and you can see Baja California.

And in a very clear day, you might see the mouth of the Colorado River.

One of the most incredible things about this place, is that is the fact that if you come don here, you█re seeing land forms you have to go to several different places in the North American continent to see.

There are lava flows that are found here, maybe in Hawaii, maybe in a few other places.

But here we have all of them.

It can be extended probably to 15-30 thousand years ago that the last major events took place here.

In terms of geology, that is a flash.

That is very close to where we are now.

One of the reasons we see things differently here than we do in for example the Northwest, is because the variety of lava here was much more basic.

There was a lower silica in the lava, which meant higher viscosity, flow structures are different and were not getting the violent explosions that typically we find with for example, Mount St. Helens with the top that blew off.

And because there's so little rainfall, we have so little vegetation and there are so many studies that show the impact vegetation has on erosion, and even with the volcanic rocks like this, we find a lot of fertile soil which is ripe for vegetation, but the one thing missing here of course is the moisture produced the life-giving force for that vegetation.

When one comes to the Pinacate you're going to see maar craters, which are created when magma comes into contact with groundwater, and creates a great steam explosion, very dramatic structures, big round, profound, deep, and we can look back at the shield of the Pinacate peak, which is a composite volcano in the shape of a shield.

All around the flanks of this shield volcano, there are over 400 cinder cones.

These are small volcanoes that are a one-time thing, they come up and form and then they're done.

It's not like they're going to erupt again.

We're on top of a lava ridge here, Richard.

Why is it just one big plain?

That's the neat thing about this type of lava, it's so viscous it█s so thick, that it's not like pancake batter exactly, it█s more like a real thick biscuit batter.

It doesn't flow in all directions; it follows the path of least resistance.

So it's coming along and hits a ridge or something that's already there and goes around it It creates a new valley.

Boy, it's all over, valley ridge and none of it is easy to walk on.

No.

This particular stuff here you can see its carrying all the debris that has come across on its way down here.

Oh, yeah!

It's full of rocks.

And the barrel cactus.

Thirsty They're thirsty.

And yet, look how healthy they are.

They survive, 2 inches of rain a year, maybe 3, sometimes none at all.

One of the greatest inventions in the last two centuries is a shock pole.

These are aluminum aircraft alloy, and you take them like this and all of the sudden you have a pole, that's perfect for setting up a tent.

Even if there's a thunder storm on its way, which there never is in the Pinacate, at least, hasn't been for a couple of years.

You set it up like that.

Now you're ready for desert camping, in this area of red cone, we have ash.

Volcanic ash, it's a pumice, it is soft and you can see it moves around rather nicely, then if I indent it then I can smooth it back over, and it is the perfect place to camp.

Ash invites you to sleep, lulls you to sleep by its softnes.

It█s not like anything like, its explosive volcanic ash.

This is red-cone, remnants of a cinder cone and in the Pinacates it's where the road from the east ends and Father Kino decided to walk the rest of the way after the top.

It's red, because of the weird iron composition of the volcanic ash that came out of the volcano and some of the lava.

In every different lava flow, the composition is different, different chemistry means different color.

Red cone is known throughout the region, as the one place where its, sharp red.

I was able to come here, at the end of 1990, so that was my first time here and since then, I was just captivated by the landscape, it's unique, it's magnetic.

As it happens to all the travelers that come here, this place has extraordinary magic, it's a magnet for explorers.

It's a magnet for writers and for people looking for the aesthetics of the environment.

I happen to be in an extraordinary time, in which the United States and Mexico wanted to create reserves along the border.

And the Pinacate and the Gran Desierto reserves were really important for both countries.

This crater is 244 meters deep.

So, that's about 800 feet deep.

Yes, more or less.

And about a mile wide.

That█s a mile across?

Every decade or so, there's a pond down there that quickly disappears.

Geologists found there is a layer of travertine, somewhere there, that indicates the presence of the lake Of a deep lake.

Lake that probably was a hundred, hundred and fifty feet deep, that was full of freh water and probably many of the local fauna and migrating birds took advantage.

So, it was bird oasis.

17,000 years ago.

The great appeal of El Pinacate and Gran Desierto de altar is that there are many, many geomorphic features; features that are associated to the geography and the morphology of the land.

So, you have craters, you have cinder cones, you have granite mountains, you have great valleys and arroyos, you have gallery forests in the desert.

And then if you go west, you find the great sea of dunes, that have the great star dunes, and then the most isolated of the drylands of North America, Sierra el Rosario.

They call this the tecolote flow it's quite a steep little climb.

I don't know why tecolote, that means owls in Spanish?

How did that get in the conversation?

Beats me.

What do owls have to do with lava?

But this is vast.

It goes on and on, and on.

Man, this ins incredible.

Tell me, that is, that is a raft, right?

It looks like it's a piece of the crater from way over there, that got rafted, carried out by the lava, all this distance.

Heck, what's that?

3/4 of a mile, at least.

Maybe a mile.

And it's just sitting on top of out here, I feel like there█s a bulldozer underground, just pushing this mass along.

These big chunks are actually pieces of the original lava flow probably that came from the top and broke up as the energy kept pushing.

But the cinders down here on the ground, this is actually, probably chunks of cinder from the crater, because it was a cinder cone.

So, this stuff gets locked in the lava, maybe in big blobs and gets more easily broken down.

Down here, we have very fine clay soils.

That will support as we call the creosote bush.

Well as we progress towards the crater, then we see the brittle bush that grows in coarser soils.

When I look at Cerro Colorado, first off the color is different you don't see the dark lavas all around What geologists said that there were, sort of little lakes around, which, one remains close by.

So, when the volcanic activity occurred, it went through layers of mud.

That's we see mud everywhere here.

That's why.

Yes, yes, yes just lift the mud, and there were explosions and there was hydrothermal activity and there were lots of water and steam, magma contacted the mud and the water table, and then there was an explosion and another, and another.

And that can be seen in the walls.

Cerro Colorado is isolated from the rest of the east side of the range, no roads laid across, we must return to Mexico Highway 2, which parallels the border with the United States,for more than 20 miles,to reach the west side.

The west side roads are unimproved dirt tracks,sometimes obscured by blowing sand or washed out by an occasional flash flood.

Weeks may go by, without a single vehicle passing through.

Back in the late 1960s, NASA was trying to train astronauts to ride in vehicles on the moon.

And now we know that the astronauts practicing here left some graffiti, part of a 10,000 year old history of graffiti here.

The area here is so well suited to a keep the record, that it has endured since the 1970s here, as paintings or engravings have endured 10, 000 years in the Pinacate region.

Throughout the Pinacate, everywhere you look the rocks become almost the same color, with this kind of shiny surface.

This luster that most rocks of the Pinacate have, because they have remaining C2, and they have been buried in the same position for thousands of years.

Nothing else grows, but this microorganism that they deposit a layer of minerals on top of the rock.

So, this rock has been here for many thousands of years and had time to develop the varnish and underneath, it looks just kind of like an ordinary piece of rock.

No varnish on top.

This is called El Trébol, which actually in Spanish means clover leaf.

It's a maar crater, but what's unique about it is has three loaves, it is said that there is a fourth loave in this one.

So, there were, it looks like there were three eruptions, which created this maar.

Probably very close together.

And if you walk the perimeter of this, you can see where the fourth one probably was.

This place is called Tinajas de los Papagos or Papago Tanks it is the most reliable and accessible supply of water, guaranteed water in all of the Pinacate.

It has been here and known by indigenous people for thousands of years and they relied on it as they move back and forth between the Gulf of California and the North.

Primarily bringing salt.

There are clear indications that people have been here before, these are little water holes in the salt and the lava .

And here is a huge one, and it's beautifully round, it could not be anything but a place where women and maybe some men sat to grind.

What did they grind, Alberto?

What did they make here?

The staple here was mesquite pods, you would have the whole pod of the mesquite and you have to grind it, and many other things of course, you can add some tribulus that you collected.

Squash, corn.

These were the blenders of the time.

The landscape here is sort of bleak, all lava, but you do have the glorious Palo Verde.

And when you have to live here, The O'odham after whom the Papago Tanks are named, base their annual calendar on the reproductive cycle of the saguaro the flowering, the fruiting, they make wine.

And to find them here, would just be an additional bonus to the water and the saguaros all around here.

The saguaro is the iconic plant of the Sonoran Desert.

It invades, it's present everywhere and the law of the indigenous people of the Sonoran Desert.

God the other plant, you can't not notice, is the brittl.

Brilliant yellow gold.

And there's one with the red center that is Encelia farinose.

It█s associated with water courses farther the north.

Among the many craters that Sierra Pinacate holds, Crater Sykes is my favorite.

Not only is it different from the other craters, in the sands of, there is a deepest to the diameter, but also because it has all sorts beautiful colos in its frame.

At the bottom, what we find is the collapse of the crater itself, that created a very sandy bottom.

In which there's a small plier.

when there are outpours of rain, it causes a little bit of water, as well as Elegante, at sometims Sykes had a lake inside.

Sykes is not the only crater in this small area, there are many others around, McDougal, Molina, Badillo, and Celaya .

And farther south, the crater La Luna, the moon.

About 20 miles from the southern foothills of the Sierra Pinacate is the Mexican resort on the gulf of California, called Puerto Peñasco or Rocky Point.

Today it█s a bustling tourist haven of about 60,000 people, many of them Mexican or American tourists.

50 years ago it was a small, quiet, easy going fishing village of a couple hundred people, with one street.

This new tourist magnet draws its water from the aquifer underlying the Sierra Pinacate.

It's harder to imagine a greater contrast than the frantic activity among the thousands of tourists in Puerto Peñasco and the wild desolation of the volcanic range of the Sierra Pinacate.

Many people drive south from the states into Rocky Point, just to have a good time there.

Never realizing that they are going past this amazing piece of earth, in here.

That has been decreed as world heritage by Unesco.

The sand dunes here, in the gran desierto, you can see a classic geological battle going on.

The lava flow called the Ives flow comes out of the Sierra Pinacate flows down, covering sand as it comes, meets the granites of Sierra Blanca, starts going up the side and continues.

After it cools, the winds continue and bring in the sand and the sand then covers the lava.

And until a new lava flow comes to cover the sand, the battle will go to the victor.

In this case the sand.

So, to have sand dunes, real sand dunes, you have to have two things; a lot of wind and a source of sand.

And here we have both.

Here we have both.

Strong winds in the upper gulf of California and the Colorado river carrying Rocky Mountains sand down into the mouth of the gulf.

Do you think that perhaps the sand we█re walking on, was once part of what is now Grand Canyon?

Indeed, by Yuma, it was reckoned that it had a million tons of sand that were carried every year.

Every year.

Have you ever noticed, that climbing up sand dunes is tricky?

It's tiring.

I have to tell you something important, it is a lot easier going down.

I love that.

Yeah.

As a kid, I enjoyed it so much.

The plants have not stabilized this yet.

But now we come down here and all of the sudden, here are plants.

Here's a perfect example of a plant that can survive in the dunes.

Look at this.

The trunk, originally was about 6 inches in the sand and now it's been excavated.

Sometimes you will find only the top of this plant, going out of the dune and then it deflates and the sand is carried away, and then these roots are exposed.

And they can go far....

They must be 10 meters down.

Very long.

And the dunes hold water very well, so if they want to have the roots in water they have to go down to where it is.

Well, dunes are the subjects of the whim of winds.

the whim of winds, good.

We are very lucky, here is a Ajo Lily.

We are very lucky, Aren't they beautiful?.

Aren't they beautiful?

One, one.

But in good years, there are thousands, perhaps millions of them.

Very tall.

Covering the whole desert.

They have a bulb, just like any lily that you plant, right?

And they have a storage bulb underneath and they, when it rains then, they will pick up that moisture and store it in that bulb, and get carried away.

Yes, just to survive by the season, and a wait for the expected good winter rains.

We can still see the faint outline of the city of Puerto Penasco, the dunes, which I'm standing, seem to present a buffer or barrier or protectie coating for the Pinacate biological reserve.

Beyond us, is a wilderness that needs to be protected, forever.

♪ Join us next time in the americas with me David Yetman They are producers of oxygen and absorbers of greenhouse gases.

Tropical rainforests are among earth's great drivers of climate.

They are producers of oxygen and absorbers of greenhouse gases.

Part of expanded researchinto how our planet operates... are two different sites dedicated to expanding our understanding... of these huge reservoirs of life.

The Biosphere in Arizona and the rain forest of Costa Rica.

I don't have my hat on.

It's alright, this is sort of like behind the scenes of what it takes to make good television Dave is slaving away in the kitchen He volunteered to bring breakfast That's because in the morning Dave does something Restless activity proves a man -Goethe Funding for In the Americas with David Yetman was provided by Agnese Haury Funding for In the Americas with David Yetman was also provided by the Guilford Fund.

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